1. Field of the Invention
The present invention relates to the transfer of impact or knocking force from a mechanically, pneumatically, or hydraulically driven knock- or impact-beating device. This device is mounted externally of a container or tank which receives dust-laden, hot, and/or contaminated gases, onto heating or cooling surfaces that are installed within the container and are to be intermittently cleaned. The present invention also relates to a device for effecting such a transfer of the impact or knocking force.
2. Description of Prior Art
The necessity for cleaning heating or cooling surfaces which are installed within a container or tank, and around which circulate dust-laden, hot, and/or contaminated gases, results from the requirement to assure a constant heat transfer between a gas and the heating or cooling surfaces. A number of methods and devices for cleaning these heating or cooling surfaces by means of mechanically, hydraulically, or pneumatically driven knock or impact-beating devices are known. The cleaning effect is achieved in that the heating or cooling surfaces, and the deposits adhering thereto, undergo different accelerations due to the different inertias resulting from the transferred knocking or impact energy, as a result of which the deposits fall from the heating or cooling surfaces. The differences among the heretofore known methods and devices result from the operating conditions which exist in the containers which inclose the heating or cooling surfaces. Thus, for example to transfer the knocking or impact energy onto the heating or cooling surfaces, which are installed on the gas side of containers operated at a pressure that is greater than the surrounding atmospheric pressure, and which are used, for example, in a pressure-type coal gasification plant with a pressure of about 40 bar on the gas side; with the knock or impact-beating device being mounted externally of the pressure tank or container, a portion of the knocking or impact energy must be utilized to overcome the internal gas pressure of the container. One reason for disposing the impact-beating or knock device externally of the container is that the cooling surfaces within a pressure-type coal gasification container have gases with a temperature of about 1800.degree. C. flowing therearound. Therefore, if the knock device were disposed within the container, additional cooling devices would be necessary for this device. U.S. Pat. No. 4,457,361 Premel et al, issued July 3, 1984, and belonging to the assignee of the present invention, discloses a knock or impact-beating device for such a pressure-containing container. With this patented device, by means of a pressure-equalizing connection element, nearly the entire applied knocking or impact energy is transferred to the heat exchanger surfaces which are to be cleaned.
A common feature of all such heretofore known devices is that the elements which transfer the impact or knocking energy must be sealed off. This is true whether a working cylinder is utilized within the container, as disclosed in German Offenlegungsschrift No. 24 11 133, whether striker rods are used which push through the container wall, as disclosed in German Offenlegungsschrift No. 22 40 250 or whether a connection element is used for a pressure tank to transfer the knocking or impact energy, as disclosed in the aforementioned U.S. Pat. No. 4,457,361 Premel et al issued July 3, 1984 and belonging to the assignee of the present invention. However, great drawbacks arise from these heretofore known devices since the seals thereof are exposed to high thermal or mechanical stresses due to the dust-laden and/or hot or corrosive gases. In cases in which the gases are furthermore contaminated, there exists the danger of environmental pollution, so that additional, expensive safety devices are necessary. Furthermore, the use of sealing elements entails close fits with small tolerances, so that when dust-laden gases flow around the heretofore known impact-beating or knock devices, the susceptibility to problems is necessarily great; as a result, these sealing elements must be frequently serviced. In addition, the advantage of simple servicing or replacement which a knock or impact-beating device which is mounted externally of a container has over a device disposed within the container again comes to nothing when the design of the knock device is provided with additional sealing means to avoid operation stoppages of a unit.
An object of the present invention therefore is to make possible the transfer of impact or knocking force from a mechanically, pneumatically, or hydraulically driven knock or impact-beating device, which is mounted externally of a container that receives dust-laden, hot, and/or contaminated gases, onto heating or cooling surfaces which are installed within the container and which are to be intermittently cleaned. According to features of the present invention, the sealing problems of the heretofore known knock or impact-beating devices can be avoided, and the impact or knocking energy can be transferred as completely as possible onto the heat exchange surfaces which are to be cleaned, even in the case of a container that is operated at a pressure greater than the surrounding atmospheric pressure.